Improved Hydrogen-Sensing Properties of a Pt∕SiO[sub 2]∕GaN Schottky Diode

Pt ∕ SiO 2 ∕ GaN (MIS) and Pt ∕ GaN (MS) Schottky diodes exhibit hydrogen-sensing characteristics, including forward sensitivity ratios ( S F ) of 14685 and 603.9, reverse sensitivity ratios ( S R ) of 44636 and 5626 (in 9970 ppm H 2 ∕ air ), and Schottky barrier height variations ( Δ ϕ b ) of 231.6 and 195.9 meV (in 9970 ppm H 2 ∕ air ) at 300 K , respectively. As compared with the MS device, the studied MIS device manifests a larger hydrogen-detection capability. This result implies that the SiO 2 insulator surface plays a strikingly important role in producing the excellent hydrogen-sensing response. Furthermore, reproducible responses at various temperatures are also realized.